Infrastructure refers to the fundamental facilities and systems serving a country, city, or area,1 including the services and facilities necessary for its economy to function.2 It typically characterises technical structures such as roads, bridges, tunnels, water supply, sewers, electrical grids, telecommunications, and so forth, and can be defined as "the physical components of interrelated systems providing commodities and services essential to enable, sustain, or enhance societal living conditions."3

Uses of the term

Engineering and construction

Engineers generally limit the use of the term "infrastructure" to describe fixed assets that are in the form of a large network, in other words, "hard" infrastructure. Recent efforts to devise more generic definitions of infrastructures have typically referred to the network aspects of most of the structures, and to the accumulated value of investments in the networks as assets. One such effort defines infrastructure as the network of assets "where the system as a whole is intended to be maintained indefinitely at a specified standard of service by the continuing replacement and refurbishment of its components".7

Military

Military strategists use the term infrastructure to refer to all building and permanent installations necessary for the support of military forces, whether they are stationed in bases, being deployed or engaged in operations, such as barracks, headquarters, airfields, communications facilities, stores of military equipment, port installations, and maintenance stations.8

Critical infrastructure

The term critical infrastructure has been widely adopted to distinguish those infrastructure elements that, if significantly damaged or destroyed, would cause serious disruption of the dependent system or organization. Storm, flood, or earthquake damage leading to loss of certain transportation routes in a city, for example bridges crossing a river, could make it impossible for people to evacuate, and for emergency services to operate; these routes would be deemed critical infrastructure. Similarly, an on-line booking system might be critical infrastructure for an airline. These elements of infrastructure are often the focus of recovery efforts in the aftermath of natural disasters. Damage to critical infrastructure could also result in a public safety hazard.

Urban infrastructure

Urban or municipal infrastructure refers to hard infrastructure systems generally owned and operated by municipalities, such as streets, water distribution, and sewers. It may also include some of the facilities associated with soft infrastructure, such as parks, public pools and libraries.

Green infrastructure

Green infrastructure is a concept that highlights the importance of the natural environment in decisions about land use planning.910 In particular there is an emphasis on the "life support" functions provided by a network of natural ecosystems, with an emphasis on interconnectivity to support long-term sustainability. Examples include clean water and healthy soils, as well as the more anthropocentric functions such as recreation and providing shade and shelter in and around towns and cities. The concept can be extended to apply to the management of stormwater runoff at the local level through the use of natural systems, or engineered systems that mimic natural systems, to treat polluted runoff.1112

Marxism

In Marxism, the term infrastructure is sometimes used as a synonym for "base" in the dialectic synthetic pair base and superstructure. However the Marxist notion of base is broader than the non-Marxist use of the term infrastructure, and some soft infrastructure, such as laws, governance, regulations and standards, would be considered by Marxists to be part of the superstructure, not the base.13

Other uses

In other applications, the term infrastructure may refer to information technology, informal and formal channels of communication, software development tools, political and social networks, or beliefs held by members of particular groups. Still underlying these more conceptual uses is the idea that infrastructure provides organizing structure and support for the system or organization it serves, whether it is a city, a nation, a corporation, or a collection of people with common interests. Examples include IT infrastructure, research infrastructure, terrorist infrastructure, employment infrastructure and tourism infrastructure.

Related concepts

The term infrastructure is often confused with the following overlapping or related concepts.

Land improvement and land development

The terms land improvement and land development are general terms that in some contexts may include infrastructure, but in the context of a discussion of infrastructure would refer only to smaller scale systems or works that are not included in infrastructure because they are typically limited to a single parcel of land, and are owned and operated by the land owner. For example, an irrigation canal that serves a region or district would be included with infrastructure, but the private irrigation systems on individual land parcels would be considered land improvements, not infrastructure. Service connections to municipal service and public utility networks would also be considered land improvements, not infrastructure.1415

Public works and public services

The term public works includes government owned and operated infrastructure as well as public buildings such as schools and court houses. Public works generally refers to physical assets needed to deliver public services. Public services include both infrastructure and services generally provided by government.

Infrastructure in the developing world

According to researchers at the Overseas Development Institute, the lack of infrastructure in many developing countries represents one of the most significant limitations to economic growth and achievement of the Millennium Development Goals (MDGs).16 Infrastructure investments and maintenance can be very expensive, especially in such as areas as landlocked, rural and sparsely populated countries in Africa.16 It has been argued that infrastructure investments contributed to more than half of Africa's improved growth performance between 1990 and 2005, and increased investment is necessary to maintain growth and tackle poverty.16 The returns to investment in infrastructure are very significant, with on average thirty to forty percent returns for telecommunications (ICT) investments, over forty percent for electricity generation, and eighty percent for roads.16

Regional differences

The demand for infrastructure, both by consumers and by companies is much higher than the amount invested.16 There are severe constraints on the supply side of the provision of infrastructure in Asia.17 The infrastructure financing gap between what is invested in Asia-Pacific (around US$48 billion) and what is needed (US$228 billion) is around US$180 billion every year.16

In Latin America, three percent of GDP (around US$71 billion) would need to be invested in infrastructure in order to satisfy demand, yet in 2005, for example, only around two percent was invested leaving a financing gap of approximately US$24 billion.16

In Africa, in order to reach the seven percent annual growth calculated to be required to meet the MDGs by 2015 would require infrastructure investments of about fifteen percent of GDP, or around US$93 billion a year.16 In fragile states, over thirty-seven percent of GDP would be required.16

Sources of funding

Currently, the source of financing varies significantly across sectors.16 Some sectors are dominated by government spending, others by overseas development aid (ODA), and yet others by private investors.16

In Sub-Saharan Africa, governments spend around US$9.4 billion out of a total of US$24.9 billion.16 In irrigation, governments represent almost all spending. In transport and energy a majority of investment is government spending. In ICT and water supply and sanitation, the private sector represents the majority of capital expenditure.16 Overall, between them aid, the private sector, and non-OECD financiers exceed government spending.16 The private sector spending alone equals state capital expenditure, though the majority is focused on ICT infrastructure investments.16 External financing increased in the 2000s (decade) and in Africa alone external infrastructure investments increased from US$7 billion in 2002 to US$27 billion in 2009. China, in particular, has emerged as an important investor.16